Sarin

This topic is hard to comprehend. There is another thing about supercharging, at low alt when throttle is partially closed, MP will increase while reducing engine rpm, so going from high power setting in to low power setting require throttle readjustment as well. So let say MP goes from 40 to 30 inch then you reduce rpm from 2400 to 2100 during that process MP will rise. Above critical alt things looks opposite.